
let wof ={
    'add':function(a,b){
        return a+b;
    },
    'jian':function(a,b){
        return a-b;
    },
    'cheng':function(a,b){
        return a*b;
    },
    'chu':function(a,b){
        return a/b;
    },
}
module.exports=wof;